To be honest - the only evidence is what I read here too. With hard, narrow saddles, the two bones on the bottom of your pelvis are supported on the back part of the saddle - but can be a bit painful on the muscle between the bones and the saddle until you get used to it. The nose of the saddle is to help you 'grip' and balance the bike going round corners and such. With the padded saddles, your sit bones push down through the padding to the bottom but the padding is compressed around them and the padding around that is pushed down a little bit by the other parts of your bum. Think of it like putting your hand down fingers-first onto a hard wet surface - only the tips of your fingers get wet. Now if you were to do that onto a sponge, your fingers would disappear into the sponge and the whole of your hand would come into contact with the sponge and get wet. It's this padding comping into contact wit the other parts of your undercarriage that causes the bloody circulation probs etc.